Valve gear of duplex pumps



Apr. 24, 1923. 1,453,029

` A.l H. TWELLS v VALVE GEAR OF'DUPLEX PUMPS Filed Aug. 20,' 1919 2 sheets-sheet 1 /l\ b1 (L b2 FICQ .*b' a bz 'bfi/agi hid-eg' ,QQ/W2k 'b' L b2 F|C;5.'

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` A. H. rwELLs VALVE GEAR 0F DUPLEX PUMPS Filed Aug. 2o, `1919 2 sheets-shura Patented Apr. 24, 1923.

UNITED STATES y ltisana prrr-13h11y oFFIcF..

ARTHUR HUGHES TWELES, OF LEICESTER, .E1\`.\'GrIAl\TD.rk

VALVE GEAR lOF DUPLEX PUMPS.

Application led AugustgZO, 1919. Serial No. 318,697. i

To all 'whom t may concern:- n

Beit lmown that 1,'. ARTHUR HUGHES TWELLs, ya subject. of the King of Great Britain and Ireland, residing at 213 Melton Road, in the township 'of Leicester, in thecounty of Leicestershire and Kingdom of England, have invented a newy and useful Improvement in Valve Gears of Duplex Pumps,-of Which the following. is a speciication; and I do l declare the' following to bea full, clear, and exact description of the invention, such as Willenable. othersskilled. in :the art to Which itappertains to .make

anduse the same.

The object of my invention .1s .to provide means for' obtaining expansion .of steam orV yother gases in the cylinders of` duplex pumps, having the .valve gear for which .a U.. S. Patent No. 1296234, 1919, has beenv granted to me.

I propose to use ajout-ofi:` valve Working infconnection With the slide valve, vvhichr valves A.Wouldbe' mounted to cut off thev steam supply to each end of the cylinder,4

this..cutoi'l"` valve could be actuated by the slidevalve,A a certain amount of free move.

mentwheing.. permitted between-.the slide valve andthe cut-olf valve and means pro-k vided for preventing the movement of theV cut-off'valve during the free ymovement of the slide valve. `The cut-off valve might alternately be actuated-by the valve spindle'` engaging with the cut-off valve inside thek steam chest or the cut-off valve might he provided. With. its lown valve yspindle ycar#k ried. through a separate stuffing boxon the steam chest I,and `actuated, from the main valve spindle-by tappets or the vlike, and

means could beprovided for regulating andv varying .the eut-off by this method the' cut-oli' would be regulatedautomatically by` thesspeed ,of the pu.mp,I propose tof`actu. A

` to'gthe exhaust, Vand kthe rightehand vend to ate thecut-ol'f valve from the movable full crum V4upon which the .actuatinglever' .of the slide Avalve' is mounted, orFfroma .con-J nect-ion--on actuatingA lever Ior alternatively rmnthe lever vofthe vpump,"`in eachf. easei a suitable reduction"gear'i would "be pro-" vided to reduce the amount of movement to that required by they cut-oli valve, andmeans could be provided by which the point of cut-off could be determined and altered asv required, such means might be conveniently attached tothe before mentioned levers or to the'. reduction gear.

The method of obtaining the required cut-ofi' would be ,modiiied to suit piston valves or Corliss valves. I Will noW describe my invention Withthe assistance of in Which:-

the' accompanying four sheets of drawings Figs. 1 to 10 sheT sectional views of slide` and cut-oli' valvesin different 'working positions.

Figi 111,-av longitudinalsection through steam chest, slide Valve and cut-QE` valve. Fig; 12,-.- is a cross section through1 steam chest and valves, at'section line w-y in Fig. '11.

Fig.. 13,--shevvs cut-off lvalve with independent'valve spindle and regulating gear. Fig. 141,-sheivs alternative connection to actuating lever.

Figs. 15, 16, and 17,.-shew sections throughv steam cylinder, slide and cut-off valves, and the arrangement of gear actuated bythe main pumplever,` which operates'the movable vfulcrum of the opposite pump.

Fig. j18,f-`she\vs a method of obtaining variable cut-oil" by gear fixed-tomain pump lever.

InFig. 1, af istheexhaust'port, b1 andfbz, the main vsteam ports.,r c the cylinder face, dnthe additional slide valvey face, e the main slide'. valve,y f Mld g, the steam ports 'through' the main slide valve", hl"and.j,w`the cut-off valves..

In Figs. 1 to 10,-,-similarletters refer to similary parts. i

In 'Fig1, the cutfoi valvesy 7b and j areishewn in their eXtreme position so that they do .not cause any cut-oil' which is done bythe'main 'slide valve only, at the' end ofv Thev slidey valve e,`is shevvn` the stroke. in mid positiomsteam being cutoff from both endsbfthe cylinder. In v2, the' ett, open-- slide valvehas been moved to the inggthe'left-hand end of the: steam cylinder steam. vvIn4v Fig. 3,-the slide` valve has been brought back 'to' mid-position, ythe piston .having reached the end of its stroke, and

thelslidevalvehas cut olsteam kto port 62.

slide valve to the extreme right, the left hand end oi' the cylinder being now open to steam and the Vright hand to eXhaust. In Fig. 5,-the movement of the pump crosshead and the valve actuating lever has brought the slide valve (2, once more to mid-position. At this point by means of the adjusting gear Z, sheWn in Fig. 11, the cut-,off valves 7L and j are brought nearer together. ln Fig. 6,--the slide valve has come into Contact with the cut-o3 valve 7u and has moved it to its extreme lett position and as the expansion valves 7i and j are connected together, the cut-oli' valve j has also been moved to the lett, so that its cutting oil edge projects over the right hand edge of the steam port 9. In Fig. 7 the slide valve moves toward midposition but before reaching it, and therefore before the piston reaches the end of its stroke, the steam to the right hand end of the cylinder is cut off b v the edge of the cut-oli valve j meeting the left hand edge of the port g of the slide valve, the rest oi the stroke of the piston being performed i by the expansion of the steam in the cylinder. Fig. 8 shevvs the position of the slide valve when the piston reaches the end of its stroke, from which it will be seen that though the steam has been cut ofi' early the port 51, has only just closed to exhaust, While the slide valve is ready to admit live steam through the ports f and 221 to the left hand end of the cylinder. Fig. 9 shews the position of the cut-oft' Valve after the movement of the slide valve to the right moving the cut-0H:l valve y', and therefore the cut-oli' valve 7L also to the right. Fig. 10 shews the steam being cut olf to the left hand end of the cylinder, but the port b2 is still open to permit the escape of the exhaust steam from the right end of the cylinder. ln Fig. 11 is sheivn the adjusting gear for altering the cut-ofi` a spindle n screwed with right and left hand thread engages with tapped holes in the cut-off valves: the end of the spindle next to the adjusting gear is square in section, and is slidable in a square socket forming the inside end of the adjustable spindle L which is providedwvith a collar, stuliing-box and gland, and the outer end of the spindle is squared to suit a spanner or handvvheel. The turning oit the adjusting screw varies the distance between Vthe cut-0H valves, Withoutpreventing free movement in a longitudinal direction. A spring 70, prevents the movement of the cut-olf valves during the free movement of the slide valve. Fig. 12 is a cross section through steam chest and valves.

In'Fig 13 m is the main slide valve spindle and 0, the separate cut-off valve spindle, p shevvs adjustable tappets actu# ated by the projection p2 on the mais Figs. 15, 16, and 17 q is the steam cylinder of one pump unit in section, r the piston, s the crosshead, t the main pump lever, u the movable lulcrum actuated b v the main pump lever of the other unit, o is the valve actuating lever, w the lever actuating the cut-off valve, n1 the links connecting cut-oli' valve lever to fixed stud or adjustable pin on main lever oi' pump; the movement of the main pump lever t directly controlling` the movement of the cut-off valve. ln Fig. 15, the piston r is 4at the eXtreme lett position, the slide valve is closed, it having been brought to the closed position by the lever o pivoting` on t-he movable fulcrum u which is brought to bear against the iXed stop y when the pumpy moves from right to left.y

The lever t has opened the valve `of the opposite pump through its movable ulcrum and valve actuating lever, and the opposite pump near the termination ol? its stroke operates the movable fulcrum 'a, moving it to the.y right as sheivn in Fig, 16, and b v means of the valve operating lever o mounted on the movable fulcrum, opening the slide valve d, so that steam enters the lett hand end of the cylinder, causing the piston fr With levers fu and t and fw to move to the right Where the parts Willbe as shewn in Fig. 17` Where it Willbe seen that the main lever 't, through the link m and lever 10, has moved the cut-oli valve from left to right,while the valvev actuating lever 0). Working on the movable Jiulcrum ma, which novv bears ron the right band stop a has'brought the main slide valve e to mid-position. but the cut-ott valve has cut ofi" the steam b v the edge 0., traversing the port f in the slide valve as thev pass each other in diiferent directions. ln the position shevvn in Fig. 17, the main lever t, has started the opposite pump which in its turnvvill move the movable fulcruin from the position therein shevvn ,against stop z, up to stop marked yf, and moving the slide valve so as to admitsteam to the rightY hand end of the steam cylinder` the expansion valve how- ,lever 15, link w, and lever 11), and cuts oli1 the steam to the cylinder by sliding over y the port g of the slide valve as the slide valve is brought back from left to right to mid-position by the valve actuating lever. Fig. 15 shews the slide valve brought back to mid-position, steam having been cut off by edge a2 of cutoff valve traversing port 57, or' the slide valve vas they pass each other in opposite directions.

Fig. 18, shews a simple method of varying the cutoff by altering the amount of movement of the cut-off valve, the end of the link a; being adjustable as regards its distance from the ulcrum of lever t, by a nut and screw adjusted by toggle nuts, or the like. When the end of the link is in the Y highest position or nearest to or coinciding with the fulcrum, there is no cut-oit by the other pump and having a certain .amount of free movement in respect of such pump crosshead, whereby the valve for each cylintuating fluid thereto, valve actuating 'leversr operated by the crosshead of each pump,

movable fulcrums supporting said levers, vstops to limit the movement of said fulcrums, each nlcrum being moved by the other pump and having a certain amount of y free movement in respect of such pump crosshead, whereby the valve for each cylinder is opened by the other pump and closed by its own pump, a separate cut-olf valve working in combination with the valve for each cylinder, means to actuate said cut-off valve` and regulate said valve to vary the eut-01T.

In testimony whereof I aiiiX my signature in presence of two witnesses.

ARTHUR HUGHES TWELLS.

Witnesses:

FRANK RUDDOCK, LYDIA MARY TWELLS. 

